The present invention is a Monolithic Sampler that may be incorporated into a wide variety of instrumentation systems that are used to sample waveforms. More specifically, this innovative monolithic design constitues an improved extremely high speed sampler that utilizes a shock wave generator to achieve bandwidths that exceed 100 GHz (100 billion cycles per second).
The basic design of sampling circuits is well known to persons skilled in the art of electronics. At the most fundamental level, a sampler is an apparatus that mixes two signals: an input waveform that must be analyzed, and a periodic train of short duration pulses which samples the input waveform at different points in time along its radio frequency (RF) cycle. The input waveforms are reconstructed sample by sample at a lower intermediate frequency. A pulse generator or oscillator establishes the rate of measurement for the sampler. When coupled to some input source that produces a voltage that varies with time, the sampler takes a tiny sample or snapshot of the input waveform which can then be displayed or processed. The quality of the measurement provided by a sampler is largely dependent upon the number of times that an input signal is sampled and the duration of the sampling pulses. Generally, high measurement speed is accomplished by providing a successive stream of very narrow, rapid, sharply-defined pulses which, in turn, affords a more accurate detection or assay of the input.
In conventional electronic instruments, the highest measurable frequency is limited by design constraints and by the components which are employed. The most severe limitation that inhibits the extension of sampler bandwidths above 25 GHz has been the constrained capabilities of the pulse generators that drive conventional sampling circuits. The useable bandwidth of pulse or comb generators that have been used to drive conventional samplers is generally only one fourth of the sampler's bandwidth. The most common pulse generators use silicon step recovery diodes, which have performance limitations based upon the carrier transit time inherent in the silicon material from which they are fabricated.
Another factor which inhibits the high frequency capabilities of currently available sampling instruments are the relative inefficiency of the discrete electronic components which comprise their circuitry. Large discrete capacitors, resistors, and diodes mounted together on a printed circuit board require costly fabrication processes that depend upon precise mechanical alignment and inevitably cause unacceptably high levels of electrical feedthrough at the sampler input ports. Parasitic and inductive capacitance propagated by discrete components generates crosstalk among conductor lines in the circuit and severely degrades the output signal developed by the sampler. This interference also limits the highest possible intermediate frequency that can be extracted from the sampler. One known solution to these drawbacks is to form each of these discrete elements on a substrate which results in an integrated monolithic sampler.
The development of more and more complex electronic instrumentation has produced a concomitant demand for faster and more sophisticated sampling equipment. The problem of meeting this demand by producing an extremely high speed, accurate, and reliable sampler has presented a major challenge to designers in the electronics industry. The development of an improved sampler that could break the 100 GHz bandwidth barrier would represent a major technological advance in the field of electronic instrumentation. The enhanced quality of measurements that could be achieved using such an innovative device would satisfy a long felt need within the industry and would enable instrument manufacturers and users to save substantial expenditures of time and money.